1. Technical Field
Embodiments of the present disclosure may generally relate to inverter circuits.
2. Related Art
As the operation time of semiconductor devices increases, performance and reliability of the semiconductor devices may be degraded. This degradation may be due to electrical and temperature stresses. Particularly, characteristics of PMOS transistors included in the semiconductor devices may be degraded due to a negative bias temperature instability (NBTI) phenomenon. This again, may cause performance degradation of the semiconductor devices.
The NBTI phenomenon means that a threshold voltage (an absolute value) of a PMOS transistor increases to reduce an on-current and a switching speed of the PMOS transistor after the PMOS transistor is turned on for a long time. That is, if the PMOS transistor is exposed to a condition causing the NBTI phenomenon, operation timing of the PMOS transistor may change. This may lead to timing errors of internal circuits of the semiconductor device. These timing errors may cause degradation of the performance and reliability of the semiconductor device.